mmc: sdhci: Drop sdhci_free_host()/sdhci_pltfm_free() interface

>From now on, all calls to sdhci_free_host()/sdhci_pltfm_free() have been
cleaned up, so we can just delete them.

Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Link: https://lore.kernel.org/r/8adcfef00fd4bc40f33f5fd42d2e5e73d72e68e4.1749127796.git.zhoubinbin@loongson.cn


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>